17,900 research outputs found
A Game Theory-Based Obstacle Avoidance Routing Protocol for Wireless Sensor Networks
The obstacle avoidance problem in geographic forwarding is an important issue for location-based routing in wireless sensor networks. The presence of an obstacle leads to several geographic routing problems such as excessive energy consumption and data congestion. Obstacles are hard to avoid in realistic environments. To bypass obstacles, most routing protocols tend to forward packets along the obstacle boundaries. This leads to a situation where the nodes at the boundaries exhaust their energy rapidly and the obstacle area is diffused. In this paper, we introduce a novel routing algorithm to solve the obstacle problem in wireless sensor networks based on a game-theory model. Our algorithm forms a concave region that cannot forward packets to achieve the aim of improving the transmission success rate and decreasing packet transmission delays. We consider the residual energy, out-degree and forwarding angle to determine the forwarding probability and payoff function of forwarding candidates. This achieves the aim of load balance and reduces network energy consumption. Simulation results show that based on the average delivery delay, energy consumption and packet delivery ratio performances our protocol is superior to other traditional schemes
On the Energy Efficiency of LT Codes in Proactive Wireless Sensor Networks
This paper presents an in-depth analysis on the energy efficiency of Luby
Transform (LT) codes with Frequency Shift Keying (FSK) modulation in a Wireless
Sensor Network (WSN) over Rayleigh fading channels with pathloss. We describe a
proactive system model according to a flexible duty-cycling mechanism utilized
in practical sensor apparatus. The present analysis is based on realistic
parameters including the effect of channel bandwidth used in the IEEE 802.15.4
standard, active mode duration and computation energy. A comprehensive
analysis, supported by some simulation studies on the probability mass function
of the LT code rate and coding gain, shows that among uncoded FSK and various
classical channel coding schemes, the optimized LT coded FSK is the most
energy-efficient scheme for distance d greater than the pre-determined
threshold level d_T , where the optimization is performed over coding and
modulation parameters. In addition, although the optimized uncoded FSK
outperforms coded schemes for d < d_T , the energy gap between LT coded and
uncoded FSK is negligible for d < d_T compared to the other coded schemes.
These results come from the flexibility of the LT code to adjust its rate to
suit instantaneous channel conditions, and suggest that LT codes are beneficial
in practical low-power WSNs with dynamic position sensor nodes.Comment: accepted for publication in IEEE Transactions on Signal Processin
mTOSSIM: A simulator that estimates battery lifetime in wireless sensor networks
Knowledge of the battery lifetime of the wireless sensor network is important for many situations,
such as in evaluation of the location of nodes or the estimation of the connectivity,
along time, between devices. However, experimental evaluation is a very time-consuming
task. It depends on many factors, such as the use of the radio transceiver or the distance
between nodes. Simulations reduce considerably this time. They allow the evaluation of
the network behavior before its deployment. This article presents a simulation tool which
helps developers to obtain information about battery state. This simulator extends the
well-known TOSSIM simulator. Therefore it is possible to evaluate TinyOS applications
using an accurate model of the battery consumption and its relation to the radio power
transmission. Although an specific indoor scenario is used in testing of simulation, the simulator
is not limited to this environment. It is possible to work in outdoor scenarios too.
Experimental results validate the proposed model.Junta de AndalucÃa P07-TIC-02476Junta de AndalucÃa TIC-570
Energy aware performance evaluation of WSNs
Distributed sensor networks have been discussed for more than 30 years, but the vision
of Wireless Sensor Networks (WSNs) has been brought into reality only by the rapid advancements
in the areas of sensor design, information technologies, and wireless networks
that have paved the way for the proliferation of WSNs. The unique characteristics of
sensor networks introduce new challenges, amongst which prolonging the sensor lifetime
is the most important. Energy-efficient solutions are required for each aspect of WSN design
to deliver the potential advantages of the WSN phenomenon, hence in both existing
and future solutions for WSNs, energy efficiency is a grand challenge. The main contribution
of this thesis is to present an approach considering the collaborative nature of WSNs
and its correlation characteristics, providing a tool which considers issues from physical
to application layer together as entities to enable the framework which facilitates the
performance evaluation of WSNs. The simulation approach considered provides a clear
separation of concerns amongst software architecture of the applications, the hardware
configuration and the WSN deployment unlike the existing tools for evaluation. The
reuse of models across projects and organizations is also promoted while realistic WSN
lifetime estimations and performance evaluations are possible in attempts of improving
performance and maximizing the lifetime of the network. In this study, simulations are
carried out with careful assumptions for various layers taking into account the real time
characteristics of WSN.
The sensitivity of WSN systems are mainly due to their fragile nature when energy
consumption is considered. The case studies presented demonstrate the importance of
various parameters considered in this study. Simulation-based studies are presented,
taking into account the realistic settings from each layer of the protocol stack. Physical
environment is considered as well. The performance of the layered protocol stack in
realistic settings reveals several important interactions between different layers. These
interactions are especially important for the design of WSNs in terms of maximizing the
lifetime of the network
Energy-delay bounds analysis in wireless multi-hop networks with unreliable radio links
Energy efficiency and transmission delay are very important parameters for
wireless multi-hop networks. Previous works that study energy efficiency and
delay are based on the assumption of reliable links. However, the unreliability
of the channel is inevitable in wireless multi-hop networks. This paper
investigates the trade-off between the energy consumption and the end-to-end
delay of multi-hop communications in a wireless network using an unreliable
link model. It provides a closed form expression of the lower bound on the
energy-delay trade-off for different channel models (AWGN, Raleigh flat fading
and Nakagami block-fading) in a linear network. These analytical results are
also verified in 2-dimensional Poisson networks using simulations. The main
contribution of this work is the use of a probabilistic link model to define
the energy efficiency of the system and capture the energy-delay trade-offs.
Hence, it provides a more realistic lower bound on both the energy efficiency
and the energy-delay trade-off since it does not restrict the study to the set
of perfect links as proposed in earlier works
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